Abstract
Maturity date (MD), defined as the duration between the first calendar day of the year and maturity, and fruit development period (FDP), defined as the duration between full bloom and maturity, are highly variable in peach [Prunus persica (L.) Batsch]. There is a need to discover molecular markers associated with these traits in order to enhance the efficiency and reliability of breeding for extending the harvest season in peach. An association mapping population consisting of 132 peach accessions was phenotypically evaluated for MD and FDP, and genotypically characterized using the genotyping-by-sequencing (GBS) approach. The phenotypic and genotypic data collected were used to conduct a genome-wide association study (GWAS). The GWAS identified three SNPs on chromosome 4 that are significantly associated with both FDP and MD. These three SNPs covered a region of 43,067 bp; we referred to this region as the MD/FDP locus. Seven genes were identified in the MD/FDP locus. One or more of these genes is believed to regulate some aspect of maturity in peach. The data reported here is expected to aid in marker-assisted seedling selection (MASS) targeted towards widening peach germplasm for maturity, particularly early maturity.
Highlights
Fruit maturity is highly variable in peach [(Prunus persica (L.) Batsch]
The objectives of the current study were to (1) examine the variability of Maturity date (MD) and fruit development period (FDP) that lies within several genotypes of peach, (2) identify SNP markers and genomic regions that associated with the traits evaluated, (3) investigate the putative functions, based on searches for orthologs, of some of the genes that co-located with the identified SNPs or within the genomic regions identified by the genome-wide association study (GWAS)
These genotypes are grown in several other localities within Canada and the United States of America (USA), and an assessment of Genotype x Environment (GxE) interactions and their influence on MD/FDP is conceivable
Summary
Fruit maturity is highly variable in peach [(Prunus persica (L.) Batsch]. The genetics of peach fruit maturity has only recently been studied and very little is understood regarding this important marketing trait. Bassi et al classified early, mid and late-maturing peach cultivars as those genotypes that have an FDP up to 90, 91–125 and over 125 days, respectively[5]. One generation of selection for late ripening and long FDP genotypes would result in a 40–90% (64–93 day) increase in maturity time[13]. Bassi et al used six progenies from controlled crosses of early, mid and late maturing cultivars to study the heritability of MD/FDP5. Crosses between early-maturing x late-maturing cultivars produced offspring that tended towards lateness[5] Such different patterns of frequency distribution for MD/FDP observed by Bassi et al suggested that a few oligogenes and some minor genes with an additive effect act together to regulate this trait[5]. The mixed frequency distribution patterns observed for MD/FDP indicate that the cross combination ability between parents used for a cross plays an important role in determining whether progeny will lean towards earliness or lateness[5,14]
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